Audible railroad signal



Oct. 24, 1939. w. c. EAvEs AUDIBLEl RAILROAD SIGNAL Filed Aug. 14, 1935O R 54 VES INVENT W/LL/AM C Patented Oct. 24, 1939 UNITED STATESlAUDIBLE RAILROAD SIGNAL William C. Eaves, Astoria Heights, N. Y.,assignor of forty per cent to Carl H. Fowler, New York, N

Application Aug-ust 14, 1935,V Serial No. 36,152

9 Claims.

My invention relates to a sound device, particularly though notexclusively adapted for an audible railway signal or the like. y.

When compressed airis directed against an elastic or elastically mountedmember, such as a diaphragm through an inlet pipe positioned closelyadjacent the diaphragm, the diaphragm will be vibrated due to static airpressure against the diaphragm tending `to move the diaphragm away 10from the inlet pipe and the inherent springiness of the diaphragm or theresilient mounting thereof tending to move the diaphragm back toward theinlet Vpipe due to the lowered pressure induced by the escape oi airfrom the inlet pipe. Signals 15- involving an air inlet pipe' andvibrating dia-'- phragm have heretofore been employed.

It is the principal object of my invention to provide a sound device ofthe character indicated wherein the efficiency is greatlyV increased`over 20. those heretofore employed.'

It is a more specific object to provide a sound device involving an airlvibrated diaphragm in which the airv employed for vibrating thediaphragm is modulatedfor the production of sound 25. Waves.

It is another object to provide a diaphragm vibrated or held by theaction of compressed air and actuated byother means.

Another object is tok provide an improved valve 30. arrangement for asound device of the character indicated.

Another object is to provide an improved form ofrdiaphragm. l

Anotherobject is to provide a more naturally 35. balanced sound deviceboth' asrto construction,

design and operation.

Other objects and various features of invention will be hereinafterpointed out or will become apparent to those skilled in the art. l 40 Inthe drawing which shows, for illustrative purposes only, preferred formsof the invention- Fig. 1 is a central sectional View rthrough a signaldevice, such as a railway signal, and illustrating features ofthe/invention;- 45 Fig. 2 is -a view in elevation of the valve seat asviewed'from the left in Fig. 1;

Fig. 3 is a View similarto Fig. 1 but illustrating a modification;

Fig. 4 is a fragmentary-view illustrating the 50 diaphragm. valve seat`andV associatedv parts of Fig..3 as viewed from the leftyand j Fig..5 isa view similar to Fig. 1 but illustrating a further modification.

In said drawing 5 indicates an air-tight` casing 55` which may serveas asupport forrthe-device, A

valve seat designated generally 6 is secured to the casing and in theform illustrated is secured to an annular plate l, which is secured asby means of screws 8 to the casing 5'. A resilient metallic diaphragmvalve member 9 is positioned between the 5 plate 'l and main casingportion 5 and is securely held thereon. The diaphragm is preferablyprovided with means to prevent the radial movement of its outer edgeduring actuation. As illustrated, the diaphragm is provided with anannularly eX- 10 tending bead Ill, so that when the center of thediaphragm is vibrated or actuated any tendency toward radial movement ofthe outer edge of the diaphragm where held by the screws 8- will beminimized and a tight joint maintained.

In the particular form shown in Fig. l the diaphragm is imperforate andis urged, as by means of a spring l l adjustable by a screw l2, towardand substantially into contact with the valve seat t.

The valve seat 6 is of improved form and prefer- 20 ably comprises aplurality of plates l3-Ili-l5, having grid slits lB-Il-IB therein, whichare arranged in staggered relation so that, as will be later described,the air will be broken up into-ine streams and thus more effectivelycontrolled or modulated for the production of eiective sound waves.Furthermore, by providing two or more plates the effective grid openingsmay be readily changed by shifting the plates relatively to each otherto vary the size of the passages through said plates. It will be notedthat the grid-openings in the plates l3-I4--l5, respectively, arepartially offsetk with relation to each other so that air currentspassing therethrough will tend tor converge in the expansion chamber 2|within the wall 20 35 from opposite sides of the center of said platesas air streams and waves flow into said chamber. The bottom of theexpansion chamber is preferably about coextensive with the valvev andthen contracts toward the throat 22, after which it opens out into anysuitable horn device.

The diaphragm l0 is vibrated by means of its own inherent resiliency,plus the effect of air directed thereagainst. yIn the form shown thevalve-seat 6 is centrally apertured for passage of 45 the inlet end 23of an air inlet pipe 24. The air inlet end 23 is positioned in contactwith or in close proximity to the central portion of the diaphragm 9 andthe inherent stiffness of the diaphragm or the adjustable spring l l orboth nor- 50.

mally tends to urge the diaphragm into engagement with or in proximityto the inlet end 23, as will be clear. Now, when air under pressurepasses through pipe 24 and control valve 25 the static pressure of theair will move the diaphragm f5 9 away from the inlet end 23 andconsequently will separate the diaphragm and the valve seat 6i. The airwill then escape between the diaphragm valve and the valve seat and theair escaping at a rapid rate will lower the pressure at the inlet end 23permitting the diaphragm to spring back so as to close the space betweenthe diaphragm and the valve seat. The diaphragm will thus be rapidlyvibrated, as will be understood. The air discharged from the inlet end23, instead of owing in a fairly uniform manner and is modulatedeifectively and effectively produces sound waves in the expansionchamber, which are contracted in the throat 22 before reaching theexpanding horn.

In the particular form shown in Fig. 3 the cas"- ing 26 is normallyairtight and the diaphragm 21,'

is secured between the edge of the casing and an annular plate 28. Thediaphragm may be provided with a bead, as heretofore described.. Theexpansion chamber member 29 is secured to the plate 21 to hold the outeredge of the diaphragm and carries a grid 30, which may be of the sameform as that disclosed in Fig. 1 but for convenience is shown merely asa single grid plate. The diaphragm 21 is also provided with gridopenings, which are sufliciently staggered in relation to the openingsin the grid 35 sothat when the diaphragm seats on the grid there can beno escape of air and when the diaphragm is unseated air may escape fromeither side of the diaphragm through the grid. The diaphragm ispreferably provided with other openings 3| to permit the free passage ofair to both sides of the diaphragm.

Air for actuating the diaphragm enters throughv an inlet pipe 32 and anannular passage or groove 33 and thence through bores 34 to thediaphragm. The diaphragm, if desired, may be indented, as shown at 35,to form a fairly effective valve to seatwith the openings constituted bythe bores 34. The action of the vibrating diaphragm in the presentinstance is substantially the same as that heretofore described inconnection with Fig. 1, that is, the air escaping from the bores 34 willvibrate the diaphragm and the escaping air will pass to both sides ofthe diaphragm and when the diaphragm and valve seat are separated in thevibratory movement of the diaphragm the air will escape from both sidesof the diaphragm through thev grid valve seat 30, that is to say, sincethe diaphragm is in the form of a grid valve the air from the airtightcasing 26 will pass through the grid valve and then through thegridvalve seat, while air on the opposite side of the diaphragm` willpass merely through the grid valve seat and the air will thus bemodulated and sound waves pro` It is to be understood that` thediaphragm 21 is preferably assisted in its movement toward its seat by aspring 36 backed up by an adjusting screw 31. In order to avoid thepossibility of the accumulation of such anexcess of air pressure in thecasing 26 as would impair the operativeness of the device I prefer toemploy an adjustable relief valve 38 for releasing such eX- cess.

In the particular form shown in Fig. 5 the construction of the casingand expansion chamber is substantially thesame as heretofore described.However, in this form the diaphragm 40 has a central, substantiallyimperiorate, portion 4.6 po- 1326; In operation air pressure against thediaphragm` causes it to become momentarily unseated from the inlet 45,permitting air to flow into the space or expansion reservoir back of thediaphragm 40, from whence it ilows through the grid passages by which itis modulated. As the air flows from thepipe 45 into the reservoir backof the-"diaphragm and thence through the lgrid passages,y the pressurenecessarily decreases so that the diaphragm will again return to itsseat.

In this case the diaphragm does not function toA entirely close thepassages in the grid 42 and hence rapid vibration of the diaphragm willoccur and the rapid, intermittent flow of air through the gfridvpassageswill effect the desired modulation.

While'the 'present invention is described as being embodied in a signal,such as a railway signal or the like, it is tobe understood that theair, for example,'from the air inlet pipe 24 of Fig. l could be employedfor maintaining the diaphragm in a fairly balanced position and thediaphragm could be actuated or vibrated by means'such as the voice coilof a loudspeaker or the'like, so as to cause the escaping air to bemodulated in sound reproduction rather than as hereinrdisclosed.

Air as used herein means any gas or vapor capable of producing thedesired sound effects.

While the invention has been described in considerable'detail andpreferred forms illustrated, it is to be understood that various changesand embodiments maybe made, all within the scope of the invention as'defined in the appended claims.

.I claim: -1. In a device of the character indicated, a diaphragm valve,a rigid grid valve seat adjacent thereto, and an air inlet pipe havingits outlet positioned between said seat and diaphragm valve to directair against said diaphragm valve to separate said valve andV seatwhereby air from said inlet pipe will escape between said diaphragm andvalve seat and be modulated in passing through lsaid grid valve seat.

2. In a device of the character indicated, a

rigid 'grid valve seat, a diaphragm grid valve for coaction therewith,and air inlet means for directing air under pressure against apart ofsaid diaphragm valve for moving the same in the direction of its seat,saidl diaphragm valve having passage means for permitting air from saidair inlety pipe to flow to both sides of said diaphragm' valve andthrough said grid seat whereby air from said air inlet pipe will pass toboth sides of said diaphragm valve and escape through said griddiaphragm valve and valve seat and be modulated thereby.

3. In a device ofthe character indicated, a grid valve seat, a 'griddiaphragm valve for coaction therewith, said valve and valve seat beingnormally spaced from each other, and an air inlet pipe positioned todirectk compressed air aigainst Ysaid'grid diaphragm valve for movingthe 'same in the direction of its coacting seat,

whereby air escaping from said air inlet pipe will tend to close saidvalve and when said diaphragm valve springs back to tend to close saidair inlet pipe, air which has previously escaped from said air inletpipe will pass through said grid diaphragm valve and valve seat and bemodulated thereby.

4. In a' device of the character indicated, a rigid grid having aplurality oi outlet air passages, a resilient vibratory diaphragm forcoac- ,f

tion therewith as a valve, an air inlet pipe positioned to supply airpressure on one side of said diaphragm to unseat it from said grid topermit air to flow through the passages in said grid, an expansionchamber to permit momentary air pressure reduction beyond said air inletto permit said diaphragm to move in the opposite direction, andadjustable means to vary the speed of vibra- `tory movement of saiddiaphragm.

5. In a device of the character indicated, a valve seat means, aresilient vibratory diaphragm valve for coaction therewith, an airinletl pipe positioned to direct compressed air to one side of saiddiaphragm for moving the same from its seat,` an expansion space beyondsaid air inlet to permit air pressure to drop beyond said inlet to allowsaid diaphragm to return, said valve seat means including a grid platehaving a plurality of outlet air passages in communication with saidspace when the diaphragm is unseated, a sound chamber overstanding theoutlet side of said grid and contracted toward its outer end, and a hornextending from said contraction.

6. In a device of the character indicated, a

' grid valve seat, a valve for coaction therewith, and means forsupplying air for passage past said seat, said grid valve seatcomprising a plurality of superposed plates each having grid openingstherein, the `grid openings of adjacent plates being arranged inoverlapping relationship.

7. In an audible signal, a 'grid member comprising a plurality ofsuperposed plates having grid openings therein, openings of adjacentplates being arranged in staggered relation, with a sound producingresilient diaphragm co-acting therewith as a valve.

8. In an audible signalling means, a casing, a grid plate at one endthereof havin-g a plurality of openings therein, said casing including asound chamber contracted at its outer end and overstanding all of saidgrid openings, a resilient diaphragm valve mounted to vibrate in saidcasing to the rear of said grid plate and having chambers on oppositesides thereof, an inlet pipe for conducting compressed air to one sideof said diaphragm to flex it in one direction relatively to said gridplate by air pressure, said valve operating to open and close thepassage of air from said pipe to one of said chambers to permit said airpressure against said diaphragm to drop when open to allow saiddiaphragm to flex in an opposite direction, the passages in said gridplate being in communication with air in said casing While said airinlet pipe is open thereto to permit air to flow through said gridpassages for the purpose described.

9. In a device of the character indicated, a pair of relatively movableplates, both of said plates having a plurality of grid valve openings,passage of air through said openings being controlled by the position ofsaid plates, one of said plates being resilienty the other being rigid,and means for directing air under pressure against said resilient platefor vibrating the same relatively to the other of said plates andmodulating the air flow through said grid openings of both said plates.

WILLIAM C. EAVES.

